DNA-Überstrukturen für neuartige Konzepte in der plasmonischen Sensorik

A core element of the localized surface plasmon resonance (LSPR) sensors is their suitability as a transducer, which converts the binding event into a measurable signal. Since the strength of the signal depends on the electromagnetic field of the nanoparticle and the surrounding medium, signal amplification methods such as directional resonance coupling with biofunctionalized gold nanocubes and self-organizing structures such as hybridization chain reaction (HCR) and DNA origami can be applied. DNA nanotechnology enables optimization of nanostructure design and improvement of sensitivity and detection limits of LSPR sensors for future point-of-care (POC) detection systems. DNA-origami-gold-nanocube-dimers as nanosensors represent an approach for highly sensitive single-molecule detection. A protocol was developed which enabled the biofunctionalization of surfactant-capped gold nanocubes. Another approach for highly sensitive detection is the combination of HCR and LSPR for the detection of a microRNA specific for asymptotic lung cancer. Here, linear amplification is employed to increase the low sensitivity of label-free, LSPR-based biosensors and to specifically detect concentrations of 1 pM analyte, which is within the detection range for body fluids typical for miRNA. Since the volume of each analyte injection was 50 L, the LSPR biosensor can detect about 50 attomole miRNA. The ability to work with such small volumes of diluted miRNA solution should make the biosensor method compatible with the available volumes of patient samples from liquid biopsies and the required preliminary sample processing procedures. The biosensor presented is practical, simple, scalable, powerful, and suitable for the point-of-care detection of miRNA in the future. The work presented was thus able to demonstrate the potential of DNA nanotechnology for LSPR-based biosensor technology in various ways.